This invention relates to an improved vertical lathe capable of carrying out milling and turning operation to a workpiece.
A vertical lathe for carrying out milling and turning operations comprises a spindle assembly including a hollow ram having a front end portion provided with an inner tapered surface and a hollow spindle journaled by a bearing in the hollow portion of the ram and provided with a front end portion having an inner tapered surface. A turning tool is secured to the front end of the ram when it is operated and a milling tool is secured to the front end of the spindle when operated. The tapered hole of the ram for the turning tool has a diameter larger than that of the spindle for the milling tool. At the attachment of these tools, both tools are inserted into the hollow portion of the ram and pulled upwardly into the hollow portion of the spindle to secure them to the spindle assembly.
With the vertical milling and turning machine of the type described above, at the milling operation, a first shank portion having small diameter of the milling tool engages the tapered portion of the spindle and a second shank portion having large diameter is spaced from the tapered portion of the ram, and on the other hand, at the turning operation, a first shank portion having small diameter of the turning tool is spaced from the tapered portion of the spindle and a second shank portion having large diameter engages the tapered portion of the ram. Thus, during the milling operation, dusts and swarves are likely intruded into a gap between the second shank portion of the milling tool and the tapered surface at the inner front end of the ram. In addition, during the turning operation, since the turning tool is secured to the ram by a key member, for example, if the spindle is erroneously rotated, the spindle assembly and the tool will be damaged.